Fastening means



Patented oct. 29, 1935 PATENT oFFicla:g

2,019,049 FAsTENiNG MEANs i William E; Hoke, Baltimore, Mil., assignorto Dardelet Threadlock Corporation, New York, N. Y., a corporationxofDelaware Y Application April 8, 1932, Serial No. 603,916l

V v 3 Claims. Important Objects of the present invention are,

to provide an improved fastening device having the desirablecharacteristics of both a bolt and a rivet, and to provide an improvedtight-holding releasable fastening means designed for satisfctorlyjoining structural steel parts and the li e. A f

Other Objects of the Invention will appear herei'nafter.

In the drawing, Fig. -1v is a side view of the bolt member of thefastening device;

Flg. 2 a sectional view of a joint structure embodying the fasteningdevice;

Fig. 3 va section on the line 3 -3 of Fig. 1; and

Flg. 4 a sectional side view showing a modification of the bolt element.

The fastening means includes a bolt l and a nut 2; .The bolt comprises ashank 3 having a rounded head 4 at one end and a thread 5 at its oppwiteend. e Between the head and the thread the shank is serrated to formhelically arranged projections in the form of ribs 6 extending aroundand along the shank, Vpreferably from a point spaced slightly from thehead to a point at or adjacent the thread .5. Between the head and theadjacent ends of the ribs the shank has a neck l of less diameter thanthe ribbed portion of the shank. Said ribs are arranged in a continuousseries around the shank and each rib describes a portion of a 'steephelix coiled in a reverse direction to the coil of the thread 5. Incross section the ribs are preferably of approximately ratchet toothform. The face of each rib directed obliquely toward the head 4 isdisposed at an abrupt angle to the axis and the circum- -ference ofthe-shank while thesface directed 'ribs the bolt blank will preferablyhave a cylindrical shank portion, of greater diameter than the maximumdiameter of the thread 5. The ribs may, however, be formed otherwisethan by the rolling method. A i Y The thread 5 of the bolt and thethread 8 of V the nut are complementary threads of equal and constantpitch, and are the well-known Dardelet type of screw thread disclosed inUnited States v wise displacement.

(oras-1) Patent No. 1,657,244. 'The nut thread and the root of the boltthread slope inward and make an angle of preferably six degrees with'the threadI axis, this being within the angle. of friction of the metalor metals of the threads. The ribs of the I threads are much narrowerthan the grooves to permit relative lcrosswise displacement "of thethreads in an axial direction' for self-looking mutual engagement ofsaid sloping crest and root looking surfaces. The threads also haveopposed, 10 coactive abutment surfaces making an abrupt angle with theaxis to p'osvitively limit said cross- At its abutment face the nut hasav recessin the form ofA a counterbore 9 having a diameter ll exceedingthe maximum diameter of the threads 4and also slightly exceeding themaximum diameter of the ribbed portion of the bolt. The height of thenut substantially corresponds to the length of the threaded reducedportion of the bolt shank, S0

' and the depth of the counterbore exceeds the axial distance betweenthe adjacent end of the ribbed portion of the 'bolt and the point wherethe bolt thread begins to run out and become imperfect. -The purpose ofthe counterbore is to 25 permit the nut to be screwed fully against anabutment without obstruction by the ribs and by the imperfect inner endportion of the thread. Preferably the metal of the bolt is softer thanthe metal of the parts P to be joined. In applying the bolt'the threadedend thereof is inserted as far as it will go through registeringapertures in said parts of slightly greater diameter than said threadedend but of less diameter than the ribbed portion of the bolt. Then, byeither imp'act or steady pressure upon the bolt head the shank isforcibly driven into place. As the ribbed portion of the shank is,driven home lthe pro-. truding crests of the ribs are folded over orupset transversely of the ribs and progressively along 40 the shank toprogressively fill'the grooves between the ribs, as shown in Fig. v2.This folding over of the rib crests is facilitated by the crosssectional form of the ribs and by their helical arrangement. The bolt isso proportioned .With relation to the height of the nut and thethickness of the lparts to be joined that the ribbed head of the boltthe ends of the ribs are upset into the space surrounding the neck li.

The nut 2 is screwed upon the bolt thread and forcibly tightened to drawthe parts flrmly together. When the axial advance of the nut is arrestedand the nut is further turned without axial advance its thread isaxially displaced crosswise outward of the bolt thread and the slopingcrest surface of the nut thread is jammed into self-looking frictionaiengagement with the inclined root surface of the bolt thread. The boltshank is bound in the holes and positively resists the torque ofscrewing on and looking the nut so that there is no necessity of holdingthe bolt head against turning. The helical coiling of the ribs in areverse direction to the coil of the thread *contributes to the torqueresistance.

The bolt, the nut andthe Joined parts are bound together in a rigid,runifled Joint structure in a manner to offer powerful resistance to anyrelative movement between them-in arLvv direction. Throughout the entiredepth of the registering apertures there isa transverse bolt-workpressure which positively resis'ts transverse relative displacementbetween the Joined work pieces and also resists transverse relativedisplacement between the work pieces and the bolt. There is also anut-work pressure longitudinally of the bolt which holds the work piecesclamped together. The nut-work pressure is positively maintained by thenut-locking feature and by said positive holding of vthe work pieces andthe bolt against any transverse movement relatively to the nut. Therebyall movement tending to unscrew the nut is eliminated and the nut ispositively held against loosening due to vibration or work movement. Allparts of the Joint are rigidly bound together to vibrate in unison asthough they were integrally formed.

The fastening device can be used in place of a hot drivenrivet and ithasmany advantages thereover. It makes a stronger Joint, reduces the laborof making the Joint, avoids the objectionable noise of rivet driving andrenders the Joint releasable by unscrewing the nut and driving out thebolt. It is possibleto ob'tain a much greater compression of the Joinedparts by tighteningthe nut 2 than is obtainable by a rivet whichproduces compression solely by its cooling and contraction. Also. thelongitudinal contraction of the.rivet weakens it and the transversecontraction reduces its diameter and leaves a slight space in the holes.The cold driven bolt constantly fllls the holes and owing to this facttogether with the greatly increased compression obtainable by the nut,the Joined parts are powerfully clamped together to resist slippage andreduce the shearing strain upon the fastening means.

In structural steel riveting it is customary to first produce therequiredl compression of the Joined parts by bolting them togetherthrough the rivet holes. Then, the bolts are removed one by vone andreplaced by hot driven rivets. My improved fastening means eliminatesthe necessity of this preliminarybolting together of the parts. Theimproved cold-driven bolt may A be inserted at the start by a single,unassisted worlcman and by the employment of only a hand hammer and awrench. Much labor is thereby eliminated.

Another advantage of the bolt is its accommodation to drif of the holes,that is, a slight lateral displacement of the-holes out of accurateregister. If the reduced, threaded end of the bolt is insertable throughthe holes the ribbed portion ofthe bolt may be driven into place, therib crests upsetting to a greater or iess degree in accordance with thedrift. This avoids the necessity of bringing the holes into register bymeans of a drift pin or by'reaming them to receive an s oversizefastening element.

Fig. 4 shows a bolt element llhaving annular integral abutment ribs IOat the inner face of its head. These ribs are approximately V-shaped incross section and their peaks are adapted to 10 effect a bitingengagement with an abutting Joined part, penetrate any scale or otherirregularities which may be on the abutting part and make a secure,sealed contact with the body metal of the part entirely around the boltshank. 15 Thereby the bolt head is self-calked and made fluid-tight. Theannular ribs also enable an even` contact top be obtained when the boltis canted slightly in holes which are slightly out of register.

. The ribs will penetrate the abutting part or else upset to varyingdegrees around the' shank to eil'ect an even, continuous. engasementwith the part entirely around the shank. When the ribs penetrate thepart they also assist in holdint the latter and the bolt againstrelative transverse slippage. The bolt is shown as provided with severalof the annular ribs but in some services a single rib may be sufllcient.Except for the changes described the bolt I- is like the bolt l.

What I claim is: 80

1. A separable fastener of the kind comprisinl a headed bolt and a nuttherefor provided with coupling threads of the Dardelet self-lookingtype, characterized in that the height of the nut substantiallycorresponds to the length of the ll threaded portion of the bolt, thethreaded bore of the nut opens into an enlarged non-threaded centralrecess in the base face of the nut, and the threaded portion of the boltis Joined to Ithe bolt head by a non-threaded round shank portion of thebolt whichis enlarged from said threaded portion substantially to thebolt head to an overau diameter which is intermediaza the amin of thenut recess and the over-all diameter of said threadedV portion of thebolt by laterally u deflectable and parallel bolt-hole-wall grlppingribs thereon which are of equal length and lie in helical paths of whichthe direction of winding about the bolt axis is reverse to that of thebolt thread, each of which ribs extends from the so inner end of thethreaded portion of the bolt substantially to the bolt head.

2. A separable fastener of the kind comprisins a headed and threadedbolt and a threaded nut therefor, characterized in that the height ofthe ss nut substantially corresponds to the length of the threadedportion of the bolt, the threaded bore of the nut opens into an enlargednon-threaded central recess in the base face of the nut, and thethreaded portion of the bolt isJoined to the bolt 00 head by anon-'threaded round shank portion which is enlarged from said threadedportion substantially to the bolt head to an overall diameter` which isintermediate the diameter of the nut recess and the over-all diameter ofsaid threaded Olportion by parailel and laterally deflectablebolthole-wall gripping ribs thereon of equal length and substantiallytriangular cross section which meet base to base around the shank andlie in helical paths of which the direction of wind- 'lo ins about thebolt axis is reverse to that of the ,bolt thread, each of which ribsextends from the lnner end of the threaded portion of the boltsubstantially to the bolt head and has one side face which is steeperand of less width from base 15 to crest of the rib than its oppositeside face and is turned toward the bolt head.

3. A two-part separable fastener of the kind consisting of a nut and abolt of which the shank is provided with a head and has a threaded endportion on and oil which the nut may be screwed, characterized in thatthe bolt shank has a nonthreaded portion between its head and threadedend portion provided with a plurality of laterally deflectablebolt-hole-wall gripping ribs stepped therearound and each projectingfarther from the shank axis than the shank thread and also lying in ahelical path of which the direction of winding about the shank isreverse to that of the shank thread for lateral deflection of said ribstoward the bolt head. by forcible axial lnsertion ofsaid ribbednon-threadedportion 'of the shank in a round bolt hole in one of thepieces to be fastened, into a friction gripping relation wit'h the wallof said hole in which the frie tion grip of the shank ribs upon the wallof the hole will increase with the increase of the torque applied to theshank by the nut during subsequent screwing up of the nut upon the boltto tightly clamp the fastened pieces between the shank head and the nut.

WILLIAM E. HOKE.

